This invention relates to a mobile switching system that determines which cellular sector provides service to a mobile telephone set. More particularly, this invention relates to a process that uses a first criteria and a second criteria to determine which cellular sector provides service to a mobile telephone set. Still more particularly, this invention relates to determining which cellular sector will provide service based upon signal strength and load balancing.
In today""s society, wireless and/or cellular telephones are a common means of communication. Wireless and/or cellular telephone service is provided in the manner. A mobile telephone set transmits and receives radio signals from an antenna connected to a base station. For purposes of the present discussion, the term cellular site is hereinafter used to describe a base station and an antenna that provides telephone service to mobile telephones. A cellular sector is the term for a geographical area which is serviced by a cellular site. The base station is connected to a mobile switching system which is in turn connected to a telephone network. The base station converts between RF signals and telephonic signals to allow communication between the mobile telephone set and other telephone sets somewhere else in the telephone network.
In a typical wireless and/or cellular system, cellular sites are located in close proximity to one another and the cellular sectors of cellular sites may overlap in order to ensure that there is a cellular site that can provide telephone service to a mobile telephone set regardless of the location of the mobile set. Since the cellular sectors of cellular sites may overlap, the mobile switching system must determine which cellular site will provide service to the mobile telephone set. In a conventional wireless telephone system, the cellular site that provides service to a mobile telephone is determined by comparing the signal strength of signals between the mobile telephone set and each cellular site receiving signals from the set. The cellular site that has the strongest signal strength for signals from the mobile telephone set is assigned to provide service to the mobile set.
Resources in a cellular and/or wireless network are wasted because only one criteria, i.e. signal strength, is used to determine which cellular site provides service to mobile telephone sets. For example, a first and a second cellular site have overlapping cellular sectors. The first cellular site is providing a maximum number of mobile telephone sets with service because the signal strength between the mobile sets and the first cellular site is the strongest as compared with the signal strengths of other cellular sites and the mobile sets. Therefore, the first cellular site provides service to all of the mobile telephone sets.
Since the second cellular site does not have the strongest signal strength for any of the mobile telephones, it does not provide service to any of the mobile sets. If another mobile telephone set requests service and it is determined that the signal strength is strongest between the first cellular site and the requesting mobile set, the new mobile telephone set cannot be serviced because the first cellular site is already providing service to a maximum number of mobile telephones. From this example, it is obvious that there is a need for a system that determines which cellular site provides service to a mobile telephone set in a manner that reduces the waste of resources in a cellular/wireless system.
The above and other problems are solved and an advance in the art is provided by a system that uses two criteria to determine which cellular site should provide service to a mobile telephone set. An advantage of this invention is that resources in the cellular/wireless system are not wasted. This allows the system to provide service to a greater number of mobile telephone sets at one time.
The system of the present invention is software or firmware executed by a processing unit in a mobile switching system to determine which cellular site will provide service to a mobile telephone set. The mobile switching system then signals the proper cellular site to provide service to the mobile unit.
The process is performed by the mobile switching system in the following manner. A signal requesting service is received from a mobile set. The mobile switching system assigns one cellular site to provide service to the mobile set based upon a first criteria. It is then determined whether the assignment of the cellular site to provide service exceeded a secondary criteria. If the secondary criteria is exceeded by the assignment, the process is repeated until a cellular site that meets both the primary and secondary criteria is assigned to provide service to the mobile set.
The following in an exemplary embodiment of a mobile switching system that has software that executes the above described process. In this exemplary embodiment, the primary criteria is signal strength between the mobile set and a cellular site. The secondary criteria is the load of the cellular site. For purposes of the present discussion, the load of a cellular site is the number of mobile telephone sets that are being provided service by the cellular site.
In the preferred exemplary embodiment, the process begins when a signal requesting telephone service is received from a mobile telephone set. The mobile switching system then determines the signal strength between the mobile telephone set and each cellular site that receives the signal. The cellular site with the strongest signal strength is then assigned to provide service to the mobile telephone set. The mobile switching system then determines whether the assignment of the mobile telephone set to the cellular site causes the load of the cellular site to exceed a predetermined number such as 80% capacity. If the load does exceed the predetermined capacity, the switching system attempts redistribute the mobile sets being serviced over the cellular sites to reduce the load of the cellular site.
Since the process is used to assign each mobile set as the set requests service, the load of each cellular site is continually balanced to prevent one cellular site from reaching capacity. This better allocates the resources in the system to allow the system to handle more mobile telephone sets at one time.